Cardiopulmonary bypass (CPB) is the technique used in most open heart surgery to temporarily take over the functions of the heart and lungs, allowing surgeons to operate on a still, bloodless heart. The patient is connected to a heart-lung bypass machine, which draws blood from the venous system (usually through a large cannula in the right atrium), passes it through an oxygenator (which adds oxygen and removes carbon dioxide), and returns it to the arterial system (usually via the aorta). During CPB, the heart is stopped using a high-potassium solution (cardioplegia) and is usually cooled to slow metabolism and protect the heart muscle.
CPB is used for procedures including coronary artery bypass graft (CABG) surgery, heart valve repair or replacement, repair of congenital heart defects, and heart transplantation. The duration of bypass is a key variable: longer bypass times are associated with higher risk of complications including blood clotting changes, inflammatory reactions, kidney injury, and cognitive effects.
Off-pump surgery, in which CABG is performed on the beating heart without CPB, is an alternative in selected patients. Minimally invasive techniques using smaller incisions and partial bypass are also increasingly used.
CPB is distinct from CPR (cardiopulmonary resuscitation), which is the emergency technique used to manually maintain circulation during cardiac arrest. Extracorporeal membrane oxygenation (ECMO) is a related but different technology that can provide longer-term heart and lung support outside the operating theatre, sometimes used in refractory cardiac arrest (ECPR) or in critical care.
« Back to Glossary Index